The term "ideology" predates Marx and Engels, e.g., Antoine Destutt de Tracy (1796) coined the word to refer to the science of ideas. Since de Tracy, the term "ideology" has evolved into different meanings without definitive agreement (like "postmodernism"). Marx and Engels' definition--often simplified to false consciousness--is frequently invoked by left liberal, socialist, and anarchist critics, but is this same definition used by liberal or conservative scholars and pundits?
Michael Freeden provides a provisional definition in Ideology: A Very Short Introduction (2003). "A political ideology is a set of beliefs, opinions, and values that
(1) exhibit a recurring pattern
(2) are held by significant groups
(3) compete over providing and controlling plans for public policy
(4) do so with the aim of justifying, contesting or changing the social and political arrangements and processes of a political community"
If ideology is provisionally defined in this way, then how does it differ from political philosophy, which also offers opinions, values, and proposes sets of belief? Does the labor of philosophy transform into ideology once philosophical work evolves into a more or less defined school that then attracts mediators such as public policy think tanks and influential journals with connections to politicians, lobbyists, and academics, which streamline philosophical thought into a type of "blueprint" for implementation?
What does the (partial) phrase "...the ideological and political construction of the middle class..." mean?
Note: I didn't have a chance to pursue an independent study on ideology during my masters coursework, and our uses of "ideology" / "ideological" often strike me as problematic and not always coherent.